The present invention has as an aim a delivery and ejection device for flat elements into a machine working them, in particular into a packaging production machine intended for the manufacturing of cardboard boxes from a web or sheet material.
Such machines include several stations the ones followed by the others, typically allowing to print the used material, to cut it out according to a reference shape by means of a rotary tool for example, then to reject, on one hand, the inconvenient waste resulting from cutting and, on the other hand, all unsuitable blanks before collecting the other boxes blanks into a delivery station.
The subject of the invention is useful in this last operation. The worked sheets or cardboard web can generally include in their width several identical boxes blanks or cuttings, each one representing the shape and the developed surface of the manufactured packaging. The amount of blanks which can be thus laid out side by side depends of course on the width of the worked support, but also on the maximum suitable format for the machine and on the size of the boxes blanks.
Once achieved, these boxes blanks are laid out, into the delivery station, in parallel lines of streams on conveyor belts. This shingling, that is to say that blanks overlap one another, is due to the fact that the conveyor belts are moving more slowly than the feeding sheets or cardboard web. There are thus as much streams rows as much blanks in the width of the worked support. The streams are then regularly collected by a stacker forming piles which will finally be delivered on a carriage or, by another belt conveyor, towards a storage station for example.
Documents EP 316""477 and EP 317""330 describe similar devices which allow the quick stacking of the downwards part of a single stream of flat elements so as to be piled up. These shingling and sheets stacking devices are working continuously without needing to stop the shingling operation during the pile removal. To do so, these devices include two overlapping conveyors with parallel belts so that the second conveyor is settled onto the longitudinal axis of the first one and can slightly go up and down through the latter. Initially, the two conveyors are moved at the same speed. When the leading part of the stream includes enough sheets to make a pile of several of them, the second conveyor raises itself slightly above the plan of the first one and carries, at high speed, the corresponding stream part to deliver it onto a plate against a stop along which the aforementioned pile will take place. Initially settled in high position, this plate goes down progressively according to the sheets stacking so that the falling height of the sheets is constant in order to ensure a good stacking. The sheets pile must then be lowered until an output level where it will be removed from the plate before this last one can raise again to be able to deliver the next pile of sheets. Meanwhile, the second conveyor was lowered and replaced in its initial position under the new leading edge of the stream which was continuously travelling thanks to the regular drive of the first conveyor. A new operating time can thus start again. The operations intended for the pile formation, its removal from the plate and the raising again of this latter in its initial position must of course succeed quickly enough to avoid, in all cases, the new edge of the stream to be almost engaged and to fall too early from the first conveyor.
Another device intended to form piles of sheets starting from shingling elements is described in the document CH 633""761. It includes several conveyors, each one comprising a rolling conveyor belt arranged into the whole width of the machine. On this width, several parallel shingle stream of blanks can fit here. This device also allows to receive and pile up boxes blanks without decreasing the machine production rate which is secured to it thanks to a braking device which will stop the run of the streams. This stop will temporarily increase the thickness of the streams. The last conveyor belt is settled so that it can turn around its control shaft, which allows, if necessary, to have the streams path deviated onto another waste removal conveyor belt. This path deviation occurs if imperfections in the printing or in the manufacturing of the boxes blanks would have been scanned by control devices located upstream. The piles of each stream are then simultaneously arranged onto a carriage movable into vertical direction, then moved by a push rod onto a transverse conveyor which will remove them.
One disadvantage of this device finds its way by the stripping of the imperfectly printed blanks which must be driven out of the normal path. Depending on the nature and on the origin of the defects, one specifies that the latter can of course modify only one row of blanks, when ignoring the other rows simultaneously produced. However, in this device, the report of a defect on one part of an unspecified stream means not only the stripping of this latter but also the stripping of all other adjacent stream parts which are simultaneously onto the same conveyor belt. It generates a waste, of course undesirable, which can become proportionally significant, especially when carrying out small production series.
The document GB 2""074""990 describes another device allowing the delivery of a certain amount of sheets starting from a stream travelling continuously through a delivery station. As it is the case for almost all delivery devices, it is necessary to enter a stop in the continuous flood of the sheets stream in order to handle with a minimum necessary time for the stripping of the pile and for the replacement of the means used to deliver the next pile. To this end, the device as described in document GB 2""074""990 is made of two en to end telescopic conveyors. Each conveyor is made of an endless belt set into rotation around a plurality of tracks or rollers. The rotation speeds of these belts are interdependent the one from the others. The front end of the first conveyor and the back end of the second conveyor, which faces it, are assembled onto a same carriage which can move longitudinally forwards to backwards into the moving direction of the stream. When the stacking is almost achieved, one must deal with a stop in the stream moved by these two conveyors. To do so, the aforementioned carriage moves towards downstream and the speed of the second conveyor is increased in order to release quickly the second conveyor from its loading and to generate thus a sufficient lack of time allowing the stripping of the pile. Once the delivery support is ready to receive a new pile, the speed of the second conveyor is reduced and the carriage goes back upstream in its initial position.
Although it is running with satisfaction, this device suffers from a first defect related to the carriage size which is necessary dependent from the length of its run. Indeed, as it is performed for this invention, one can note that the length of the carriage must be in all cases more important than the maximum length of its moving. However, if one wants to reach higher production rates, it is also necessary to increase the run of the movable carriage, which means in fact to have to perform with a carriage the more longer and the more imposing. Another defect of this device results from the repeated moving of the carriage. To be able to perform the longest possible stop of the stream, it is necessary to get the carriage back as quickly as possible. However, being at evidence of a relatively large size, this carriage represents also a significant moving entity which, on one hand, requires a powerful moving mechanism and then a braking mechanism which, on the other hand, must be controlled by a massive surrounding carrying structure. Moreover, the inertia strength of this carriage continuously generates strong shocks into the machine frame. The whole range of these undesirable requests and mechanical constraints are dealing with a heavy, cumbersome and expensive equipment.
All these devices also show another disadvantage which finds its way by the stacking. This operation needs a support, movable in the vertical plan, which successively goes from a high initial position, when it is empty and ready to receive a new pile, to a low output position allowing the side unloading of the pile. Although this way of doing is reliable and works well, it needs however a whole range of operations which can only be sequentially carried out. As it seems at first to be impossible to reduce much more the useful time to carry out each separate operation, it is also impossible to reduce the total time needed to discharge the pile and to raise up again the support in its initial position, considering that the support can be raised up again only once the pile is discharged.
Another disadvantage is due to the fact that these devices, either do simply not allow to reject sheets of insufficient quality, or excessively extend this operation to a whole range of the production by eliminating all the sheets within the width of the machine. To carry out this stripping operation, another more accurate solution consists in rejecting the sheets of bad quality one by one, in a quality controlling and stripping device before these ones are shingling. However, located into the production line upstream from the delivery station, such a device is, on one hand, not intended for the stripping of already shingling sheets and, on the other hand, means an additional module for the production line, which is completely dissociated and different from the object of the present invention.
The present invention has as an aim to deal with the above mentioned disadvantages by providing a delivery and ejection device for flat elements which is fast, economic, universal and easy to deal with. With the wording economic, one will understand that this device has to be manufactured at low cost, but must also avoid any kind of waste while quickly sorting the parts which are comprised within the quality standards from those with defects having to be rejected from the production line. With the wording universal, one intends to provide a device which can suit at the same time with a whole range of goods of different formats and ensure an easy way to deal with so as to work with each one of these products while reducing as much as possible the settling operations of the delivery device between two series of different works. Thus, the object of this invention must be easily adaptable so as to deliver as well wide boxes blanks, such as for example 1 or 2 blanks in the whole width of the machine, as smaller boxes blanks numerously divided (for example 10) into the width of the machine. This device must also be able to reject quickly and with less wasting all boxes blanks which are not included within the required quality standards. One will note that to effectively suit this last speed condition, it is at this point already impossible to think of carrying out such a sorting sheet after sheet before the latter are shingling.
To this end, the present invention has as an aim a delivery and ejection device in conformity with what is stated in claim 1.